A method for preparing a low viscosity hydroxyl-terminated phenyl silicone oil

Abstract

The application belongs to the technical field of organic silicon and relates to a preparation method of low-viscosity hydroxyl-terminated phenyl silicone oil, which comprises the following steps: (S1) adding diphenylsilanediol, organic acid anhydride and an acidic catalyst into an aprotic polar organic solvent to perform acylation reaction to obtain an acylated product; (S2) adding the acylated product dropwise into an alkaline aqueous solution under stirring until the system is neutral, then performing hydrolysis and polycondensation, separating the upper oil phase after the reaction is completed, and obtaining a phenyl-containing prepolymer; and (S3) mixing the phenyl-containing prepolymer, cyclosiloxane and an alkali metal catalyst, then performing ring-opening copolymerization reaction in an inert atmosphere, and obtaining the low-viscosity hydroxyl-terminated phenyl silicone oil after purification. The viscosity of the hydroxyl-terminated phenyl silicone oil prepared by the application is low, the viscosity at 25 DEG C is 200-1000 mPa.s, the phenyl content is adjustable, there is no methoxy group, the preparation cost is low, and the preparation process is environmentally friendly.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of organosilicon, and particularly relates to a preparation method of low-viscosity hydroxyl-terminated phenyl silicone oil. BACKGROUND

[0002] The introduction of phenyl groups into the chain of polymethylsiloxane can well improve the temperature resistance and compatibility with organic resins, and can expand the application of various products prepared from the same as raw materials, such as the preparation of room temperature vulcanized silicone rubber resistant to radiation and high temperature vulcanized silicone rubber. The preparation of different active groups such as vinyl or epoxy terminated chain containing phenyl polysiloxane can be obtained by "chain extension" from low viscosity hydroxyl terminated phenyl silicone oil as raw material. The hydroxyl content of low viscosity hydroxyl terminated phenyl silicone oil is high, and the reactivity with resin is strong, therefore, the low viscosity hydroxyl terminated phenyl silicone oil has high market value, and its preparation method has become one of the technologies that organosilicon industry competes to research and develop. However, the preparation of low viscosity hydroxyl terminated phenyl silicone oil in the prior art still has the following problems: 1) the polymerization degree of the low viscosity hydroxyl terminated phenyl silicone oil prepared is still high and difficult to control, that is, the viscosity needs to be further reduced; 2) the phenyl content in the product prepared from the low viscosity hydroxyl terminated phenyl silicone oil is difficult to control; 3) the methoxy content in the low viscosity hydroxyl terminated phenyl silicone oil product is high, thereby affecting the subsequent application of the product; 4) the low viscosity hydroxyl terminated phenyl silicone oil product prepared contains ring body mixture, which is difficult to remove from the system; 5) the cost of phenyl ring body raw material is high, the preparation process is complex, and environmentally unfriendly reagents are used.

[0003] Luo Mengxian et al. (Organosilicon Materials, 2008, 22(6):335-338) used methyl phenyl cyclosiloxane as raw material, reacted with low molar mass hydroxyl silicone oil under alkaline catalyst, and prepared hydroxyl terminated polymethylphenylsiloxane by equilibrium copolymerization. In the process, the cost of the raw material of the phenyl ring body is high, and the hydroxyl terminated polymethylphenylsiloxane product prepared does not have the characteristics of being easily controlled in the low viscosity range.

[0004] CN103524740B discloses a preparation method of low tetra ring body content methyl phenyl hydroxyl silicone oil, which uses 1,3,5-trimethyl-1,3,5-triphenylcyclotrisiloxane as raw material, adds water as end-capping agent under alkaline catalyst, and reacts in organic solvent to obtain low tetra ring body content methyl phenyl hydroxyl silicone oil. The product has low tetra ring body content, but the process uses high-cost phenyl ring body as raw material.

[0005] Zhang Liping et al. (Organosilicon Materials, 2014, 28(3):145-148) used methyl phenyl dimethoxysilane as raw material, hydrolyzed and polycondensed under acidic catalyst to prepare hydroxyl terminated polymethylphenylsiloxane oligomer. Although the viscosity is low, the methoxy content in the product is high.

[0006] CN103087320B discloses a preparation method of terminal hydroxyl poly-methyl phenyl silicone oil, which comprises the following steps: firstly, preparing a silane hydrolysis product containing phenyl linkage by hydrolytic co-condensation of methyl phenyl dichlorosilane (or diphenyl dichlorosilane) and dimethyl dichlorosilane; secondly, acylating the silane hydrolysis product with acetic anhydride under the action of an acid catalyst, and then hydrolyzing the acylated product to obtain the terminal hydroxyl poly-methyl phenyl silicone oil. The viscosity of the prepared terminal hydroxyl poly-methyl phenyl silicone oil is still high, the methoxy content in the product is high, and the phenyl content in the product is difficult to control.

[0007] CN104292464B discloses a preparation method of phenyl hydroxyl silicone oil, which comprises the following steps: firstly, preparing a semi-finished product by reacting diphenyl silanediol and octamethylcyclotetrasiloxane in toluene / isopropyl alcohol under the action of a basic catalyst; secondly, end-capping the semi-finished product with a short-chain silanol silicone oil; and finally, adding a silicone phosphate ester neutralization catalyst and distilling off the solvent to remove low molecular substances, thereby obtaining the phenyl hydroxyl silicone oil. The method is carried out in a basic system, and the viscosity of the prepared phenyl hydroxyl silicone oil is high. In addition, the diphenyl silanediol and the octamethylcyclotetrasiloxane are simultaneously added, i.e., the reaction is carried out by the one-pot method. However, the diphenyl silanediol is difficult to uniformly condense into the molecular chain due to its large steric hindrance. Furthermore, a large amount of toxic toluene solvent is used, and the process steps are relatively many. SUMMARY

[0008] In view of the problems existing in the prior art, it is necessary to develop a preparation method of low-viscosity hydroxyl-terminated phenyl silicone oil, which can adjust the phenyl content in the product, has low methoxy content, and has low preparation cost and environmental protection in the preparation process.

[0009] To achieve the above-mentioned purposes, the following technical solutions are adopted in the present application:

[0010] The present application provides a preparation method of low-viscosity hydroxyl-terminated phenyl silicone oil, which comprises the following steps:

[0011] (S1) adding diphenyl silanediol, organic acid anhydride and acid catalyst into an aprotic polar organic solvent to carry out acylation reaction, thereby obtaining an acylated product;

[0012] (S2) adding the acylated product into an alkaline aqueous solution under stirring until the system is neutral, and then hydrolyzing and condensing, thereby separating the upper oil phase to obtain a phenyl-containing prepolymer;

[0013] (S3) mixing the phenyl-containing prepolymer, cyclosiloxane and alkali metal catalyst, and then carrying out ring-opening copolymerization reaction under an inert atmosphere, thereby obtaining low-viscosity hydroxyl-terminated phenyl silicone oil after purification.

[0014] Taking acetic anhydride as the organic acid anhydride, strong acid ion exchange resin as the acid catalyst, and octamethylcyclotetrasiloxane (D4) as the cyclosiloxane as examples, the reaction equation is as follows:

[0015]

[0016] The application first prepares the oily acylated product by reacting the diphenylsilanediol with the organic anhydride in a homogeneous system under the acidic catalyst, then hydrolyzes and polymerizes the oily acylated product in a heterogeneous system to prepare the low degree of polymerization phenyl-containing prepolymer, and then performs ring-opening copolymerization of the low degree of polymerization phenyl-containing prepolymer with the cyclosiloxane to prepare the low viscosity hydroxyl-terminated silicone oil. Since the hydrolysis and polymerization of the oily acylated product is performed in a heterogeneous system, the reaction is relatively mild and easy to control; meanwhile, the silicon atom is connected with two phenyl groups, and the steric hindrance of the phenyl group has a certain inhibitory effect on the polymerization reaction, so that the polymerization degree of the phenyl-containing prepolymer is relatively low; the viscosity of the hydroxyl-terminated silicone oil prepared by the ring-opening copolymerization of the low degree of polymerization phenyl-containing prepolymer with the cyclosiloxane is relatively low. That is, the process of first performing acylation reaction and then performing heterogeneous hydrolysis and polymerization is very crucial to ensure that the low degree of polymerization phenyl-containing prepolymer is first obtained, and then the low degree of polymerization phenyl-containing prepolymer is ring-opening copolymerized with the cyclosiloxane, rather than using the "one-pot method" to perform ring-opening copolymerization of the diphenylsilanediol monomer with the cyclosiloxane.

[0017] Meanwhile, in step (S3), by adjusting the use amount ratio of the phenyl-containing prepolymer and the cyclosiloxane, the hydroxyl-terminated phenyl silicone oil with different phenyl content can be prepared. In addition, the application uses diphenylsilanediol and organic anhydride as raw materials, on the one hand, the prepared product is free of methoxy group; on the other hand, compared with the phenyl ring body as raw material, the raw material cost of the application is lower.

[0018] The low viscosity hydroxyl-terminated phenyl silicone oil has a viscosity of 200-1000 mPa·s at 25℃.

[0019] Further, in step (S1), the molar ratio of the diphenylsilanediol and the organic anhydride is 1:(2.1-2.5), preferably 1:(2.2-2.5); the amount of the acidic catalyst is 1-5wt% of the sum of the mass of the diphenylsilanediol and the anhydride.

[0020] Further, in step (S1), the organic anhydride is selected from at least one of acetic anhydride, propionic anhydride and butyric anhydride; the acidic catalyst is at least one of strong acidic ion exchange resin, p-toluenesulfonic acid, camphor sulfonic acid and trifluoromethyl sulfonic acid, preferably strong acidic ion exchange resin, which is removed by filtration after the reaction; the aprotic polar organic solvent is selected from at least one of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC) and dimethyl sulfoxide (DMSO).

[0021] Further, in step (S1), the acylation reaction is performed at 75-100℃ under normal pressure with stirring for 4-10h.

[0022] Further, in step (S2), the alkaline aqueous solution is at least one of KOH aqueous solution, NaOH aqueous solution, Na2CO3 aqueous solution, NaHCO3 aqueous solution, K2CO3 aqueous solution, and KHCO3 aqueous solution, and has a concentration of 2-20 wt%.

[0023] Further, in step (S2), the hydrolysis and polycondensation is carried out at a temperature of 40-70°C, preferably 50-60°C, for 2-10 hours, preferably 3-5 hours.

[0024] In step (S2), the phenyl-containing prepolymer has a viscosity of 50-100 mPa·s at 25°C.

[0025] Further, in step (S3), the cyclic siloxane is hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), or decamethylcyclotetrasiloxane (D5), preferably octamethylcyclotetrasiloxane (D4). D3, D4, and D5 differ in ring tension, stability, and compatibility with the phenyl-containing prepolymer, and thus differ in the degree of controllability and the amount of cyclic oligomer by-products produced during the ring-opening copolymerization; D4 has moderate ring tension, is highly controllable, and produces less by-products, and is thus more suitable for industrial production.

[0026] In step (S3), the mass ratio of the phenyl-containing prepolymer to the cyclic siloxane is 1:(1-8), and the mass ratio can be adjusted according to the required phenyl content in the final product.

[0027] Further, in step (S3), the amount of the alkali metal catalyst is 10-100 ppm, based on the total mass of the phenyl-containing prepolymer and the cyclic siloxane; and the alkali metal catalyst is one of alkali metal hydroxides, alkali metal alkoxides, alkali metal siloxides, quaternary ammonium bases, and quaternary phosphonium bases.

[0028] Further, in step (S3), a co-catalyst is added, the co-catalyst is a supramolecular compound containing a macrocyclic cavity, and is at least one selected from a crown ether, a cryptand, a β-cyclodextrin, and a calixarene, preferably a crown ether and / or a cryptand; the amount of the co-catalyst is 1-10 ppm, preferably 5-10 ppm. The inventors have found that the alkali metal catalyst and the co-catalyst can be used in combination to more stably and efficiently catalyze the reaction. The possible reason is that when the co-catalyst is a crown ether or a cryptand, the crown ether or cryptand containing a macrocyclic cavity coordinates with the alkali metal ion through the lone pair of electrons of the oxygen atom to form an electrically neutral outer coordination complex. Due to the apparent charge dispersion and hydrophobic effect, the complex can be uniformly dispersed in the non-polar solvent system, thereby more stably and efficiently catalyzing the reaction. When the co-catalyst is a β-cyclodextrin or a calixarene, the hydrophobic cavity of the co-catalyst can encapsulate the hydrophobic part (such as a phenyl group) of the polymer chain to reduce the steric hindrance and facilitate the copolymerization. At the same time, the encapsulation forces the segment containing the phenyl group to remain stretched, reduces the intramolecular cyclization caused by chain folding, and makes the product a high-linear polymer, which is conducive to achieving low viscosity. The crown ether is, for example, 15-crown-5 or 18-crown-6, and the cryptand is, for example, cryptand [2.2.1] or cryptand [2.2.2]. The crown ether or cryptand is more superior to the β-cyclodextrin and calixarene, which may be due to the unique metal ion coordination ability and hydrophobic effect of the crown ether or cryptand, which can more efficiently and stably catalyze the ring-opening copolymerization reaction, while the role of the β-cyclodextrin and calixarene is more limited to the adjustment of steric hindrance, and the contribution to the catalytic activity and the inhibition of side reactions is limited.

[0029] Further, in step (S3), the inert atmosphere is nitrogen and / or argon; and the conditions of the ring-opening copolymerization reaction are stirring at 100-160℃ for 3-10h, preferably stirring at 120-150℃ for 5-8h.

[0030] Further, in step (S3), the method for purification is as follows: acid glue is added dropwise into the reaction system under stirring until the system is neutral, then the reaction system is heated to 160-180℃, and low-boiling substances are removed under vacuum for 1-2h, and the vacuum degree is-0.1MPa to-0.01Mpa. The acid glue and the base glue are common reagents in the field of silicone. The acid glue refers to a short-chain siloxane containing an acidic group, which is both a proton acid (H + donor) and a siloxane precursor, and can neutralize the basic catalyst and participate in the end-capping of the siloxane chain at the same time.

[0031] Compared with the prior art, the present application has the following beneficial effects:

[0032] 1. The low-viscosity hydroxyl-terminated phenyl silicone oil prepared by the present application has a low viscosity, and the viscosity at 25℃ is in the range of 200-1000mPa·s, and the phenyl content is adjustable.

[0033] 2、The low viscosity hydroxyl-terminated phenyl silicone oil prepared by the method has no methoxy group, and is convenient for subsequent application.

[0034] 3、The raw material of the method is relatively low in price, and the yield is high, so that the preparation cost is reduced, and the preparation process is free of toxic reagents, and is suitable for large-scale industrial production. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 The infrared spectrum of the low viscosity hydroxyl-terminated phenyl silicone oil prepared in Example 1 is shown. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme of the present application will be described in detail below. The following examples facilitate better understanding of the present application, but do not limit the present application. The experimental methods in the following examples are conventional methods, unless otherwise specified.

[0037] Example 1

[0038] (S1) 21.6 g (0.1 mol) of diphenylsilanediol, 22.4 g (0.22 mol) of acetic anhydride, and 1.3 g of strongly acidic ion exchange resin were added into 80 mL of N,N-dimethylformamide (DMF) to form a mixed solution, which was then stirred at 80℃ under 180 rpm for 6 h. After the reaction was completed, the temperature was lowered to room temperature, and the strongly acidic ion exchange resin was removed by filtration to obtain an acylated product;

[0039] (S2) The acylated product was slowly added dropwise into an aqueous KOH solution (concentration of 12 wt%) under stirring until the system was neutral, and then the temperature was raised to 50℃ for hydrolysis and polycondensation for 2 h. After the reaction was completed, the system was allowed to stand, and the upper oil phase was separated to obtain a phenyl-containing prepolymer (the viscosity of which at 25℃ was 65 mPa·s as measured by a capillary viscometer);

[0040] (S3) 13 g of the phenyl-containing prepolymer, 87 g of octamethylcyclotetrasiloxane, 2.0 mg (i.e. 20 ppm) of KOH, and 0.5 mg (i.e. 5 ppm) of 18-crown-6 ether-6 were mixed, and then stirred at 150℃ under a nitrogen atmosphere for 8 h. After the reaction was completed, acid glue was added dropwise into the reaction system for stirring until the system was neutral, and then the temperature of the system was raised to 170℃. The low-boiling substances were removed under -0.08 Mpa for 2 h, and then the system was cooled to room temperature to obtain the low viscosity hydroxyl-terminated phenyl silicone oil.

[0041] The viscosity of the low viscosity hydroxyl-terminated phenyl silicone oil prepared was 205 mPa·s at 25℃ as tested by a rotary viscometer.

[0042] The infrared spectrum of the low viscosity hydroxyl-terminated phenyl silicone oil prepared is shown in Figure 1

[0043] ​Example 2

[0044] The rest is the same as Example 1, except that a calixarene [8] arene is used instead of 18-crown-6 in step (S3).

[0045] Example 3

[0046] The rest is the same as Example 1, except that propionic anhydride is used instead of acetic anhydride in step (S1) in an equimolar amount, and the reaction conditions are adjusted accordingly; and hole ether [2.2.2] is used instead of 18-crown-6 in step (S3); specifically:

[0047] (S1) 21.6 g (0.1 mol) of diphenylsilanediol, 28.6 g (0.22 mol) of propionic anhydride, and 1.5 g of strongly acidic ion exchange resin were added to 80 mL of N,N-dimethylformamide (DMF) and stirred to form a mixture, then stirred at 90°C and 180 rpm for 6h, and after the reaction was completed, the temperature was lowered to room temperature, the strongly acidic ion exchange resin was removed by filtration, and an acylated product was obtained;

[0048] (S2) The acylated product was slowly added dropwise to an aqueous KOH solution (concentration 12wt%) under stirring until the system was neutral, and then hydrolytic polycondensation was carried out at 60°C for 2h, and after the reaction was completed, the system was allowed to stand, and the upper oil phase was separated to obtain a phenyl-containing prepolymer (its viscosity at 25°C was 52 mPa·s as measured by a capillary viscometer);

[0049] (S3) 13 g of the phenyl-containing prepolymer, 87 g of octamethylcyclotetrasiloxane, 2.0 mg (i.e. 20 ppm) of KOH, and 0.5 mg (i.e. 5 ppm) of hole ether [2.2.2] were mixed, and then stirred at 140°C under a nitrogen atmosphere for 8h; after the reaction was completed, acid gum was added dropwise to the reaction system and stirred until the system was neutral, and then the system was heated to 170°C, and low-boiling substances were removed at -0.08 MPa for 2h, and then the system was cooled to room temperature to obtain a low-viscosity hydroxyl-terminated phenyl silicone oil.

[0050] The viscosity of the low-viscosity hydroxyl-terminated phenyl silicone oil prepared by the rotary viscometer test was 247 mPa·s at 25°C.

[0051] Example 4

[0052] The rest is the same as Example 1, except that the hydrolytic polycondensation conditions in step (S2) are different, specifically:

[0053] (S1) The same as Example 1;

[0054] (S2) The acylated product was slowly added dropwise into the aqueous KOH solution (concentration 12 wt%) under stirring until the system was neutral, and then the system was heated to 70°C for 2 h for hydrolysis and polycondensation. After the reaction, the upper oil phase was separated to obtain the phenyl-containing prepolymer (the viscosity of which at 25°C was 72 mPa-s as measured by a capillary viscometer).

[0055] (S3) The same as in Example 1.

[0056] The viscosity of the low-viscosity hydroxyl-terminated phenyl silicone oil prepared was 320 mPa-s at 25°C as tested by a rotational viscometer.

[0057] Example 5

[0058] The rest was the same as in Example 1, except that the proportions of the raw materials in step (S3) were different, i.e., the amount of the phenyl-containing prepolymer was increased, specifically:

[0059] (S1) The same as in Example 1;

[0060] (S2) The same as in Example 1;

[0061] (S3) 24 g of the phenyl-containing prepolymer, 80 g of octamethylcyclotetrasiloxane, 2.1 mg (i.e., 20 ppm) of KOH, and 0.52 mg (i.e., 5 ppm) of 18-crown-6 ether-6 were mixed, and then stirred at 150°C under a nitrogen atmosphere for 8 h. After the reaction, acid gum was added dropwise into the reaction system, and then stirred until the system was neutral. Then the system was heated to 170°C, and then low-boiling substances were removed at -0.08 MPa for 2 h. After cooling to room temperature, a low-viscosity hydroxyl-terminated phenyl silicone oil was obtained.

[0062] The viscosity of the low-viscosity hydroxyl-terminated phenyl silicone oil prepared was 676 mPa-s at 25°C as tested by a rotational viscometer.

[0063] Example 6

[0064] The rest was the same as in Example 1, except that the proportions of the raw materials in step (S3) were different, i.e., the amount of the phenyl-containing prepolymer was increased, specifically:

[0065] (S1) The same as in Example 1;

[0066] (S2) The same as in Example 1;

[0067] (S3) 40 g of the phenyl-containing prepolymer, 60 g of octamethylcyclotetrasiloxane, 2.0 mg (i.e. 20 ppm) of KOH, 0.8 mg (i.e. 8 ppm) of 18-crown-6 were mixed, and then stirred at 150°C for 8 h under a nitrogen atmosphere; after the reaction was completed, acid glue was added dropwise to the reaction system, and the reaction was stirred until the system was neutral; then the system was heated to 170°C, and low-boiling substances were removed at -0.08 MPa for 2 h; and then the system was cooled to room temperature to obtain a low-viscosity phenyl silicone oil terminated by hydroxyl groups.

[0068] The viscosity of the obtained low-viscosity phenyl silicone oil terminated by hydroxyl groups was 971 mPa·s at 25°C, as tested by a rotary viscometer.

[0069] Example 7

[0070] The rest was the same as in Example 1, except that no catalyst promoter 18-crown-6 was used in step (S3).

[0071] The viscosity of the obtained low-viscosity phenyl silicone oil terminated by hydroxyl groups was 420 mPa·s at 25°C, as tested by a rotary viscometer.

[0072] Comparative Example 1

[0073] The difference from Example 1 was that steps (S1) and (S2) were omitted, and a “one-pot method” was used in step (S3) to directly perform ring-opening copolymerization of the diphenylsilanediol and the cyclosiloxane, specifically as follows:

[0074] 15 g of diphenylsilanediol, 87 g of octamethylcyclotetrasiloxane, 0.1 g of concentrated sulfuric acid, and 1.22 mg (i.e. 12 ppm) of calix[8]arene were mixed, and then stirred at 150°C for 8 h under a nitrogen atmosphere; after the reaction was completed, base glue was added dropwise to the reaction system, and the reaction was stirred until the system was neutral; then the system was heated to 170°C, and low-boiling substances were removed at -0.08 MPa for 2 h; and then the system was cooled to room temperature to obtain a phenyl silicone oil terminated by hydroxyl groups.

[0075] The viscosity of the obtained phenyl silicone oil terminated by hydroxyl groups was 4320 mPa·s at 25°C, as tested by a rotary viscometer.

[0076] Testing and Analysis

[0077] 1) Structural Analysis

[0078] Figure 1 The infrared spectrum of the low-viscosity phenyl silicone oil terminated by hydroxyl groups obtained in Example 1 was as follows: Figure 1 cm-1 -1 cm-1 -1 cm-1 -1 The peaks at 3076 cm-1, 3051 cm-1, and 1593 cm-1 were attributed to C-H stretching vibration peaks on benzene rings, and the intensities of the three peaks showed the presence of phenyl groups; the peak at 1100 to 1000 cm-1 was attributed to Si-O-Si stretching vibration peaks. -1a broad and strong absorption peak in the range of 950cm -1 to 810cm -1 a broad absorption peak due to Si-OH bond; the above proves that the product prepared is a hydroxyl-terminated phenyl silicone oil.

[0079] 2) Viscosity and phenyl content

[0080] Viscosity: The viscosity of the hydroxyl-terminated phenyl silicone oils prepared in the examples and comparative examples was tested at 25°C using a rotary viscometer, and the results are shown in Table 1.

[0081] Phenyl content: The phenyl content in the hydroxyl-terminated phenyl silicone oils prepared in the examples and comparative examples was measured by nuclear magnetic resonance, i.e. the content of phenyl was calculated by the ratio of the integral area of benzene ring hydrogen (7.0-7.5 ppm) to silicon methyl hydrogen (0.1-0.5 ppm) in 1H nuclear magnetic resonance spectrum (1H NMR), and the results are shown in Table 1.

[0082] Table 1 Viscosity and phenyl content test of hydroxyl-terminated phenyl silicone oil

[0083] Group Viscosity (mPa-s) Phenyl content (%) Example 1 205 10.02 Example 2 350 9.80 Example 3 247 9.91 Example 4 320 9.88 Example 5 676 19.98 Example 6 971 39.78 Example 7 420 9.71 Comparative Example 1 4320 7.32

[0084] As can be seen from Table 1, the viscosity of the hydroxyl-terminated phenyl silicone oil prepared in the examples of the present application is low, and the viscosity at 25°C is in the range of 200-1000 mPa·s. The viscosity of the hydroxyl-terminated phenyl silicone oil prepared in Comparative Example 1 is much higher than that of the examples, and the phenyl content is lower than that of Example 1, although the raw material usage is close to that of Example 1. As can be seen from the comparison of Example 1, Example 4 and Example 5, by adjusting the usage ratio of the phenyl-containing prepolymer to cyclosiloxane, products with different phenyl contents can be obtained, i.e. the phenyl content is easy to control. In addition, the product prepared by the present application using diphenylsilanediol and organic acid anhydride as raw materials has no methoxy group, and the raw material cost is low and the preparation process is environmentally friendly.

[0085] As can be seen from the comparison of Example 1 and Example 7, the viscosity of the hydroxyl-terminated phenyl silicone oil prepared without using a cocatalyst is higher, and the phenyl content is slightly lower, so it is preferred to use a cocatalyst. As can be seen from the comparison of Example 1, Example 2 and Example 3, 18-crown-6 and cryptand [2.2.2] are more superior to calix [8] arene.

Claims

1. A process for the preparation of a low viscosity hydroxyl terminated phenyl silicone oil, characterized in that, The method comprises the following steps: (S1) diphenylsilanediol, organic acid anhydride and acidic catalyst are added into an aprotic polar organic solvent to perform acylation reaction to obtain an acylated product; the acidic catalyst is at least one of strong acidic ion exchange resin, p-toluenesulfonic acid, camphorsulfonic acid and trifluoromethylsulfonic acid; (S2) the acylated product is added dropwise into an alkaline aqueous solution under stirring until the system is neutral, then hydrolysis polycondensation is performed, the reaction is ended, the upper oil phase is separated to obtain a phenyl-containing prepolymer; (S3) the phenyl-containing prepolymer, cyclosiloxane and alkali metal catalyst are mixed, then ring-opening copolymerization reaction is performed under an inert atmosphere, and low-viscosity hydroxyl-terminated phenyl silicone oil is obtained after purification.

2. The production method according to claim 1, characterized by, The low-viscosity hydroxyl-terminated phenyl silicone oil has a viscosity of 200-1000 mPa·s at 25℃.

3. The production method according to claim 1, characterized by, In step (S1), the molar ratio of the diphenylsilanediol to the organic acid anhydride is 1:2.1-2.5; and the amount of the acidic catalyst is 1-5 wt% of the sum of the mass of the diphenylsilanediol and the acid anhydride.

4. The production method according to claim 3, characterized by, In step (S1), the molar ratio of the diphenylsilanediol to the organic acid anhydride is 1:2.2-2.

5.

5. The preparation method according to claim 1, characterized in that, In step (S1), the organic acid anhydride is at least one of acetic anhydride, propionic anhydride and butyric anhydride; the acidic catalyst is strong acidic ion exchange resin, which is removed after filtration; the aprotic polar organic solvent is at least one of N,N-dimethylformamide, N,N-dimethylacetamide and dimethyl sulfoxide; and / or The acylation reaction is performed at 75-100℃ under normal pressure for 4-10 h under stirring.

6. The method of claim 1, wherein, In step (S2), the alkaline aqueous solution is at least one of KOH aqueous solution, NaOH aqueous solution, Na2CO3 aqueous solution, NaHCO3 aqueous solution, K2CO3 aqueous solution and KHCO3 aqueous solution, and the concentration is 2-20 wt%; and the hydrolysis polycondensation is performed at 40-70℃ for 2-10 h.

7. The production method according to claim 6, wherein In step (S2), the hydrolysis polycondensation is performed at 50-60℃ for 3-5 h.

8. The method of claim 1, wherein, In step (S3), the cyclosiloxane is hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane or decamethylcyclotetrasiloxane; and the mass ratio of the phenyl-containing prepolymer to the cyclosiloxane is 1:1-8.

9. The production method according to claim 8, characterized by, In step (S3), the cyclosiloxane is octamethylcyclotetrasiloxane.

10. The method of claim 1, wherein, In step (S3), the amount of the alkali metal catalyst is 10-100 ppm based on the total mass of the phenyl-containing prepolymer and the cyclosiloxane; and the alkali metal catalyst is one of alkali metal hydroxide, alkali metal alcoholate, alkali metal silanolate, quaternary ammonium base and quaternary phosphonium base.

11. The method of claim 1, wherein, In step (S3), a cocatalyst is further added, and the cocatalyst is at least one of crown ether, cryptand, β-cyclodextrin and calixarene; and the amount of the cocatalyst is 1-10 ppm.

12. The method of claim 11, wherein, In step (S3), a cocatalyst is further added, and the cocatalyst is crown ether and / or cryptand; and the amount of the cocatalyst is 5-10 ppm.

13. The method of claim 1, wherein, In step (S3), the inert atmosphere is nitrogen and / or argon; and the ring-opening copolymerization is carried out at 100-160℃ for 3-10h.

14. The method of claim 13, wherein, In step (S3), the ring-opening copolymerization is carried out at 120-150℃ for 5-8h.

15. The method of claim 1, wherein, In step (S3), the purification method is as follows: adding acid glue dropwise into the reaction system and stirring until the system is neutral, then heating the system to 160-180℃, and removing low-boiling substances under vacuum for 1-2h at a vacuum degree of-0.1MPa to-0.01Mpa.

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